This invention relates generally to the field of buildings and more particularly to an easily transported and relatively low-cost roof structure for modular buildings.
In recent years, the cost of conventional on-site construction of buildings has risen at a very rapid rate. The need for low-cost buildings has, consequently increased. In response to this ever increasing need for low-cost buildings, numerous manufacturers of mobile and modular homes and buildings have developed mobile structures in an effort to meet this need. The mobile home and building manufacturers have generally built structures having a substantially long, narrow, rectangular floor plan. These mobile homes and buildings are typically provided with permanent or removable wheels so that the home or building can be towed by a truck from the factory to the customer's home or building site.
In most instances, by completely fabricating the building at the factory, construction cost is reduced because mass production techniques can be used. Site preparation costs for plumbing, electric and gas hookup, and transportation, while additional to the factory fabrication cost, nevertheless result in a net cost to the customer for a completed mobile home which generally is less than the cost of constructing on site a comparable sized home by conventional techniques.
The principal drawback of such factory-constructed mobile homes and buildings, however, is that their size is somewhat restricted due to the fact that the home must be transported, fully assembled, to the building site and, consequently, the structure must comply with highway restrictions on load width and length if transportation is to be via the highways which is customarily the case. To overcome this problem, some modular buildings are manufactured in two sections. The fully assembled one-half sections are separately transported to the building site whereat they are connected together to form a larger structure.
While the approach of building modular buildings in fractional sections at the factory and thereafter assembling these sections into a larger building at the site has somewhat overcome the size problem of typical mobile homes, this approach, however, has given rise to a significant increase in transportation and on-site costs. Since the one-half sections are generally oversized loads, transportation permits are needed and special transportation rates apply so the cost of shipping each section may be very high compared to rates for conventional trailer trucks. Furthermore, once the sections reach the building site, skilled workmen and often special equipment are required to connect the building sections together. As such, the customer cost of such modular structures becomes higher and much of the savings of factory mass production is lost. Indeed, it is economically unfeasible to transport such buildings any great distance from the point of manufacture, three hundred miles being generally considered to be the maximum feasible distance to ship such buildings.
Other prior art modular buildings have included folding roof sections which, during transportation via a conventional trailer truck or a flat bed truck are positioned so as to reduce the size of the roof. Once at the building site, the roof sections are unfolded so as to form a building with a significantly larger roof size than could be transported via a conventional trailer truck or flat bed truck.
While buildings of this type overcome the problems of building size outlined above, they do present a special problem of their own in that special equipment is needed at the building site for unloading and to raise the folding roof sections. In some designs, cranes or other power equipment are needed on site to raise the folded roof sections to their final position. In other designs, the building is equipped with winches or other hand or power operated lifting mechanisms which normally are part of the building, thus adding to the cost.
Still other prior art modular buildings are fabricated in units of box-like rooms or building sections comprised of walls, floor and roof which are individually transported to the site, usually as oversized loads at correspondingly high rates. At the site, heavy rigging equipment such as a crane is required to unload and position the sections together to form a complete building. Transportation and erection costs involved with this approach have proven so high as to make the approach impractical for most applications. Furthermore, this type of modular construction does not lend itself to relocation of the building once erected, should this be a consideration.
Therefore, in view of the foregoing difficulties, it is the primary objective of the invention to provide a relatively low cost, easily and inexpensively transported roof structure for use in a modular building which can be assembled easily and inexpensively at any desired site, and subsequently relocated if desired, with a minimum of workmen and special equipment.
It is a further objective of the invention to provide a roof structure for modular buildings which is easily transported in a folded state in a single conventional trailer truck, and which is self-erecting at the desired site to form a structure significantly larger than was heretofore transportable in a single trailer truck.
It is a further objective of the invention to provide a roof structure for modular buildings which is easily transported in a folded state in a single conventional trailer truck, and which is self-erecting at the desired site to form a structure significantly larger than was heretofore transportable in a single trailer truck, and which is self-retracting into the folded configuration for transportation to another site.
In achieving these objectives, the invention is predicated, in part, on the concept of providing a folding roof structure which can be transported inside a conventional trailer and which is self-erecting as well as self-retracting at the building site.
In a preferred embodiment of the invention, the roof structure includes a central roof section having a width approximately equal to the interior width of a conventional trailer. The central roof section has two opposed side edges to which side roof sections which are slightly less in width than the interior height of the trailer, are pivotally joined. These side roof sections, when the structure is in a folded position for shipment, hang down from the horizontally disposed center section in a generally vertical disposition with the lowermost edges thereof resting on rollers, slides or the like so that the structure can be easily rolled, slid or otherwise moved into or out of a trailer. As such, the structure can be transported in a conventional trailer at standard rates rather than higher special rates which frequently apply for wide loads.
Mounted underneath the central roof section are permanent legs which can be folded upwardly during transportation so as not to contact the floor of the trailer. As the roof structure is removed from the trailer at the building site, the permanent legs are folded downwardly to provide support therefor from the ground.
The permanent support legs are constructed to telescope so that the central roof section can be lowered slightly with respect to the ground, or other support surface at the construction site. A side roof pivoting means, which in one form comprises temporary support legs pivotally attached to the underside of the side roof sections and extending therefrom to the ground, are utilized to convert the telescoping movement of the permanent legs, produced by slightly lowering the central roof section, into pivotal movement of the side roof sections to swing them upwardly from the depending folded position characteristic of shipment to their horizontal position typical of the assembled structure. An advantage of this arrangement is that the side roof sections swing from their vertical, intransit position to their erected, horizontal position with a minimum of men and without requiring any special equipment.
Once the roof is in its erected position, lightweight panelized or modular walls can be positioned to enclose the building. These walls are easily positioned by two workmen using only hand tools. Thus, the on-site costs of a building using the roof structure of the invention is kept to a minimum.
It is yet another objective of the invention to provide a roof structure for a modular building which can be transported in a conventional trailer truck in a manner such that the walls and appliances for the building, can also be transported therein, and further in a manner which facilitates with a minimum specialized lifting apparatus, site unloading of all walls and appliances from the trailer truck.
In accordance with this objective, the roof structure of the invention is folded in the trailer during transportation, much like a drop-leaf table with the leaves folded down. In this way, the central and side roof sections are adjacent the trailer top and sides, respectively, leaving substantially the entire volume of the trailer available for storing the building walls, appliances and the like.
In addition, since in this transport condition the horizontally disposed central roof section spans and is supported by the vertically disposed side roof sections, a travelling hoist can be secured to the underside of the central roof structure for travel along the longitudinal axis thereof. Once the roof structure is partly removed from the trailer truck at the desired site, the hoist can be used to lift transported cartons stored in the trailer containing walls, appliances, etc. from inside the trailer and move them onto the building pad or ground surface at the building site. In this manner, a conventional trailer truck can transport an entire modular building including appliances therefor, and such can be unloaded and the building erected at the desired site by few workmen without additional on-site equipment. Likewise, the erection process can be reversed and the folded roof and other components reloaded without additional on-site equipment for transportation to another site.